An automatic control system is known, for example, from the German patent documents DE-OS No. 27 12 327 which describes a system whereby an accelerator pedal with subsequent accelerator pedal signal transmittor produces a signal that is used, via a first storage, to control the throttle-valve opening. In the first storage a function F.sub.1 is so stored that the storage transmits an output signal which serves as a measure for the opening angle of the butterfly valve of the carburettor. In addition, the accelerator output signal is transmitted to a second storage that holds a function F.sub.2. The second storage provides an output signal corresponding with the calculated speed of rotation of the internal combustion engine. This second storage in conjunction with a comparator circuit controls a servo-adjusting device for the direct operation of the infinitely variable transmission gear.
This circuit of an automatic control system of an infinitely variable transmission gear driven by an internal combustion engine is extremely cumbersome. It requires two storage facilities to ensure, on the one hand, the control of the throttle valve opening and, on the other, the control of the infinitely variable gear unit. Furthermore, it entails the risk of faults in the control if, as a result of incorrectly stored functions in the first and second storages, optimum adaptation cannot be achieved. In this case there is no optimum adaptation of the control process of the servo-adjusting device to the regulation of the opening angle of the butterfly valve. As a result, fuel consumption would rise.